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REVISION OP THE BRITISH WILLOWS. 337 



Vari 



II. Classification. 



its of the Willows hai 



perhaps the best is that of Andersson, though even that is not 

 altogether satisfactory. . 



Andersson arranges the species in three tribes : — A. Pleiandra^ 

 B. Diandrce, C. Syrian dree. 



The essential characteristics of the Pleiandra lie in the pale 

 unicolorous scales, which fall off before the fruit ripens ; in the 

 stamens being most usually not less than three in number; and 

 in the nectary being commonly double. 



The Diandrce are distinguished by having the scales, which are 

 more or less darker-coloured in the upper part, persistent with 

 the fruit; the stamens two in number and with free filaments; 

 and the nectary very rarely double. 



The Synandrce may be recognized by the filaments of the two 

 stamens being more or less connate. 



Now whilst these points are, in the main, characteristic of 

 each tribe, they are not such decided distinctions as might be 

 desired. In the Pleiandrte, for example, the stamens, though 

 described as free, are not so in every species ; since in some, as in 

 & fragilis, they are, or appear to be, connate at the very base 

 when viewed from the back— from the front the adnate anterior 

 nectary conceals the union ; the nectary, though often double, is 

 in one sex of some species single only ; and the stamens in some 



almost 



Moreover 



scales in some species of both the other tribes are unicolorous. 



Andersson subdivides his tbree tribes into sections, and these 

 again into groups. In the Pleiandra there are two sections 

 the Tropica, with four groups, and the Temperata with three, 

 namely, 5. Amygdalince or Triandrce, 0. Lucidcs or Pentandra, 

 and 7. Fragiles or Alba:. The Biandra are divided into the 

 Microstylce (which includes 8. Lovgifolia, 9. Cinerascentes or 

 Caprea, 10. Rosea, and 11. Argentea or Repentes) ; the Podo- 

 «ty/« (12. Virescentes or Phylicifolia, and 13. Rigidce) ; and the 

 toacrogtyla; (14. Pruinosa, 15. Micantes or Viminales, 16. Mvea, 



a nd 17. Nitidula). The Synandrce have two groups only— 

 18. Incana, and 19. Purpurea. 

 Adopting Andersson's arrangement, but using in some cases 



hi 



more instructive, the 



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